1. Field of the Invention
The present invention relates to a technique for measuring information about expansion/contraction of a substrate having expandability/contractibility.
2. Description of the Related Art
A display medium, which utilizes a liquid crystal or an organic EL, etc., is widely used as the display apparatus. For example, in the production of the organic EL display device, those known as the patterning method for patterning an electrode layer and an organic compound layer include a method in which an organic compound is vapor-deposited via a shadow mask, and a method in which an organic compound is coated by the ink-jet (see, for example, U.S. Pat. No. 7,108,369).
When the organic EL display device is produced, for example, a soluble material, which has been subjected to the coating, is dried by application of heat. For this reason, the substrate, which is subjected to the patterning, is thermally deformed in some cases. Therefore, in order to process the substrate highly accurately, it is important to control the length of the substrate highly precisely.